Surface coverings that serve as flooring materials are well known. Flooring is installed over a wide variety of subfloors, ranging from concrete to layers of plywood to old flooring material. When flooring, particularly resilient flooring, is installed over concrete its performance in the area of impact resistance is substantially less than when it is installed over plywood. The performance over particle board, flake board, etc. falls between the extremes.
Even when installed over a plywood subfloor, wood underlayments such as Masonite are typically used between the flooring and subfloor to hide subfloor irregularities. This may actually diminish the impact resistance of the flooring. Wood underlayments would improve the impact resistance of flooring installed over concrete subfloors but they are impractical for that application.
In addition, flooring materials, particularly vinyl-backed flooring materials, are subject to staining which migrates from the subfloor (or wood underlayment) and into the backing to mar the face. The vinyl-backed flooring materials are unlikely to provide substantial comfort, warmth or sound-deadening because of gauge limitations related to processing, packaging, handling, for example.
Flooring underlayments are presently in the market. Soniflor of Thailand and Tarkett (Quiet-Cor) in the USA sell felt and foam underlayments. Quiet-Cor is used as a sound deadening medium for tile installations over concrete. Both of these products share a common shortcoming . . . the felt. Felt provides less resistance to damage (flexing, indent, impact), poorer heat and moisture dimensional stability, and less structural integrity than the present structure. Further, felt provides sites for staining microbe growth which are not available in a non-felt structure.
Another underlayment which is presently sold is Everlay B produced by Mondo of France. This product does have sound deadening and insulating properties and could be used to improve the durability of flooring products in a similar manner to the present structure. However, it is less desirable for several reasons: (1) its overall gauge (ca 180 mils) renders it incompatible with most residential situations, i.e. it is much thicker than would be desirable; (2) its cost is prohibitively high for most residential jobs; (3) it has a tendency to curl when interflex floors such as Armstrong's Solarian Select are adhered to it; and (4) it exhibits poor residual indentation.